Silly mistake.

WheezyRider

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Jim, before you buy a new BMS, do some simple tests to check that it is ok. Does the power level indicator on the battery work ok? Can you measure a voltage coming out of the BMS outputs?
 
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jimriley

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Jim, before you buy a new BMS, do some simple tests to check that it is ok. Does the power level indicator on the battery work ok? Can you measure a voltage coming out of the BMS outputs?
Will do, charge indicator lights up. But there is no fuse, see pics. There's an obvious blade fuse holder in those videos, the wires from charger socket go straight to the bms on mine. The display unit came on very briefly then went off.
On our narrowboat tonight, near home though. Will have a look tomorrow. I have a decent multimeter.
 

Nealh

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Hailong BMS replacements are sold look on TBK or Aliexpress.

The BMS wire colours mean nothing they can be any colour, what matters is the BMS board is marked C-, B- & P- so you just connect the thick wires accordingly.
You ideally need the same board to guarantee the sense wire JST connects other wise you have to cut the wires and solder the new ones ( one by one to prevent shorting), get the order wrong and say good bye to the BMS again.
Back to the three thick wires C- goes to the charge point.
B- is the pack voltage wire so solders to battery 0v/B-.
P- is pack voltage for discharge so connects to the discharge connector.
As I mentioned wire colour is insignificant, one is governed by the wires marked on the BMS's PCB.

For a fuse use a 25a one other wise anything less will keep blowing if you use top current.
 
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jimriley

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Hailong BMS replacements are sold look on TBK or Aliexpress.

The BMS wire colours mean nothing they can be any colour, what matters is the BMS board is marked C-, B- & P- so you just connect the thick wires accordingly.
You ideally need the same board to guarantee the sense wire JST connects other wise you have cut the wires and solder the new ones ( one by one to prevent shorting), get the order wrong and say good bye to the BMS again.
Back to the three thick wires C- goes to the charge point.
B- is the pack voltage wire so solders to battery 0v/B-.
P- is pack voltage for discharge so connects to the discharge connector.
As I mentioned wire colour is insignificant, one is governed by the wires marked on the BMS's PCB.

For a fuse use a 25a one other wise anything less will keep blowing if you use top current.
OK, thanks. To clarify - The jst wires are the thin white ones from each battery bank to the white plug? Or are you talking about the temperature sensor? The bms I found didn't have one visible, not to say there aren't connections on the pcb. Do all bms pcbs have temperature connections?

I'd looked at the wiring diagram on the bms I posted and realised about wire colour.
Not clear about the fuse size though, it's a 5 amp feed from the charger, not the main power wire, so it can't get 25a going through it, where would it be going?
Not doing anything yet till I've got it clear other than see what the meter says and report back.
 

Woosh

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I agree with wheezy.
If it still charges (LED on the charger is red, even if it's only for a few minutes), then it's the output fuse or switch.
 

Nealh

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It wasn't clear a charge fuse was being talked of, tbh one doesn't need it as the charger regulates the current feed.
 

WheezyRider

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It wasn't clear a charge fuse was being talked of, tbh one doesn't need it as the charger regulates the current feed.
I think the charger fuse is there in case someone tries to put a fast charger on the pack and tries to charge the pack faster than the pack can cope with. Also, if something goes wrong inside the charger, it's not a bad idea to have a fuse present to prevent a short in the charger turning into an inferno as the pack then discharges into it :)
 

WheezyRider

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Will do, charge indicator lights up. But there is no fuse, see pics. There's an obvious blade fuse holder in those videos, the wires from charger socket go straight to the bms on mine. The display unit came on very briefly then went off.
On our narrowboat tonight, near home though. Will have a look tomorrow. I have a decent multimeter.
If there is no fuse, the short may have caused the solder connection to the output connector to fail, or there may be a fusible link inside the wire from the BMS to the connector that has blown. You need to see if you have voltage on the output points of the BMS.
 
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WheezyRider

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Jim, you might find this thread helpful:


I ended up replacing my BMS with a better quality one in the end, but the original still worked (until I broke it! :D).
 

vfr400

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All you need to do is measure the voltage in three positions from the cell-pack ground (B-). First, the red wire from the cell-pack to get the pack voltage. That will be attached to the positive output terminal. Second, where the negative comes out of the BMS (P-) to the negative terminal to see if the output is switched on. Third, to where the yellow is attached to the BMS (C-) to see if the charging is switched on. Apart from the first, measure directly where the wires attach to the BMS. If any are not OK, you probably need a new BMS. If they're all OK, all you have to do is trace the wires to their connectors to find where they're interrupted. Simple logic!
 
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PatM

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Thanks @Woosh , I'll ring sometime this week. There's no sign of any fuse in the battery case. As for the doubting Thomases, done lots of general wiring over the years, houses, cars, completely wired my narrowboat, that's got 450ah batteries and a 135w mppt solar setup. I'm still here. Red is earth in a plug, right? :rolleyes:
As for the key fitting the charge socket, it doesn't, but the key tip is pointed enough to touch the live pin and connect with the neg outer. Which is just possibly why it should be fused like those in the video. I presume, having thunk while on a walk, that a 5amp input charge socket would be best protected with a bit more than a 5amp fuse, maybe 10amps.

I like my posts to keep everyone happy, them as likes to learn, learn, as do I. Them as likes to whinge, grumble and snipe at newbies or whoever get to do that, they are well happy. Perhaps a useful bit of info they could impart, how does one get through life without making a mistake ever? :D

Onwards and upwards, two metres apart ;)
It only takes a lapse of concentration- which we are all capable of- Well, I am! Had a battery-fire about 7 years ago- its in my old posts- Nothing I did wrong- but nearly burnt my garage down. I've also had a duff Frog battery arrive and repaired it- but it was like diffusing a bomb (again, on my past posts)
 
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jimriley

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Jun 17, 2020
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An Update, IT'S WORKING. :D :D:D
Did the tests - charger charging, tested outputs 40.7v, put it on bike, display powered up. Although I only did a brief short with the key the display had powered off. Is there a "wait a bit while it cools down" gubbins somewhere? The display must have been temporarily affected by the short circuit.
Still, thanks to all who suggested possibilities, I now know a bit more about the kit. I like to be self-reliant where I can be.